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Evacuation
a. After the system is leak checked, connect approved dual stage vacuum
pump sized to application with preferably fresh oil to evacuate the system.
b. Ensure all inline system shut-off valves and solenoid valves are fully open.
c. Evacuate the system to 300 microns.
d. A triple evacuation is recommended in case of using analog gauges as we
might not know the exact vacuum level being achieved
Charging and commissioning
Reminder
- The scroll compressor design requires system charging with liquid
refrigerant into the liquid line.
- Do not vapor charge the Water Cooled Scroll unit. After ensuring all valves
are opened and system is evacuated properly, only then start the
refrigerant charging process. Also ensure that LP cutout is not by-passed
during the charging process.
Step-by-step:
1.
Ensure that there is no power supply to the Water Cooled Scroll unit.
The liquid line solenoid needs to be kept open for the charging process and
this may require a temporary power feed to it.
2.
Connect the refrigerant cylinder to main service hose and purge line at
the manifold end.
3.
Ensure correct orientation of the refrigerant cylinder. Follow cylinder
labeling/instructions so that liquid refrigerant can be charged into the
system. This will be charged through the high-pressure side of the manifold
and Water Cooled Scroll unit liquid service valve. Ensure that at least 70-80%
of the required refrigerant charging is done by this method.
4.
The compressor can then be started, and the unit continued to be
charged (with the controlled liquid refrigerant through the suction service
valve). The quantity of charge should always be measured. See note.
5.
The system needs to be operated down to its design evaporating tem-
perature before you can be sure the charge is correct. It is at this point that
the normal refrigeration operational checks can be carried out - such as
checking the liquid line sight glass for bubbles and the operating pressures.
Refrigerant charging is regarded full/complete when the operating tempera-
ture of the system has been stable for some time and the liquid line sight
glass is clear.
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